DESCRIPTION: The transcriptional activator and repressor, p53, modulates neuronal viability after genotoxic or excitotoxic injury, but the mechanisms by which this occurs are poorly understood. In order to elucidate p53-dependent cell death mechanisms, we will use newly developed technology involving Fourier transform ionization cyclotron resonance mass spectrometry and differential stable isotope labeling of cysteine residues to characterize the proteome (the entire set of expressed proteins in a cell or tissue of interest) of cultured cortical neurons under control conditions or after treatment with glutamate or DNA-damaging agents. The speed and sensitivity of this method exceeds that of currently available 2D-PAGE methods by several orders of magnitude. The identities and expression levels of thousands of proteins, including low abundance and previously unknown species, will be rapidly obtained from complex protein mixtures extracted from cultured neurons. Adenovirus-mediated over-expression of p53, p53-specific inhibitors and p53 knockout mice will be used to manipulate p53 levels and look for changes in protein expression.